In response to repeated legal threats, a public health doctor in Italy has withdrawn advice to curtail use of a controversial drug. The drug, ezetimibe, is a key ingredient in Zetia and Vytorin, which is manufactured by Merck . The cholesterol-lowering drug has been the subject of fierce controversy because it has never been shown to improve clinical outcomes. Despite the controversy, in 2013 the drugs had combined sales of more than $2.6 billion.